This section is intended to provide a background or context to the invention recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The present invention relates generally to the field of temperature-controlled display devices (e.g. refrigerated cases, etc.) having a temperature-controlled space for storing and displaying refrigerated objects. More specifically, the present invention relates to a refrigerated case having two separate temperature-controlled spaces or zones for storing and displaying objects having different temperature requirements. Still more specifically, the present invention relates to an open-front type refrigerated case having a medium temperature (e.g. refrigerator) zone disposed in a vertically-stacked arrangement above a low temperature (e.g. freezer) zone. More specifically still, the present invention relates to an improved air curtain system for an open-front type refrigerated case having a medium temperature zone disposed above a low temperature zone.
It is well known to provide a temperature controlled display device such as a refrigerator, freezer, refrigerated merchandiser, refrigerated display case, etc., that may be used in commercial, institutional, and residential applications for storing or displaying refrigerated or frozen objects. For example, it is known to provide service type refrigerated display cases for displaying fresh food products such as beef, pork, poultry, fish, etc. Such display cases have a closed front (e.g. with doors for accessing food products stored within the temperature controlled space), or may have an open-front that uses a flow of chilled air that is discharged across the open front of the case to help maintain a desired temperature within the temperature-controlled space. Such open-front cases may also be provided as a dual-temperature zone case with a medium temperature zone separate from and disposed above a low temperature zone to facilitate storage and display of food products having different temperature requirements at the same general location. However, these known refrigerated cases with vertically-stacked dual temperature zones present a number of disadvantages. For example, a portion of the air curtain on the medium temperature zone tends to spill over the bottom of the medium temperature zone and down into the low temperature zone. The introduction of the relatively warmer air from the medium temperature air curtain (and ambient air entrained therewith) into the temperature-controlled space of the low temperature zone tends to reduce the thermal performance and efficiency of the low temperature zone and cause other adverse consequences (e.g. condensation of moisture from the ambient environment, more frequent frosting and the need to increase the frequency of defrosting the low temperature zone, etc.).
Accordingly, it would be desirable to provide an open-front refrigerated display case having vertically-stacked dual-temperature zones with an improved air curtain system that overcomes these and other disadvantages.